In different works of researchers or university documents plagiarism is defined in different ways. Most scientists in their work mention that there is no single definition of plagiarism. The definition of plagiarism in different countries and even different universities also differ or is not published officially. Due to this reason members of academic community could have different understand the essence of plagiarism and consequences and this fact may be one of the factors contributing plagiarism. The problem of plagiarism understanding is quite relevant, because students are often uncertain how to write their works. Due to this reason most scientists offer institutions and academic communities at the first stage of creation of plagiarism prevention system to discuss and officially published a clear and detailed definition of plagiarism. The purpose of this research is to identify the understanding of plagiarism by the students in HEIs of Lithuania in comparison with general understanding of this phenomenon. Students themselves confidently say they know what it is plagiarism, but empirical study showed that understanding of plagiarism among participating students’ is unambiguous as it is stated and in analyzed scientific publications and this understanding not satisfying academic community. Comprehensive and clear definition of plagiarism and various types of it with practical examples could help the academic community to develop plagiarism prevention